The Year 11 (Preliminary HSC) Chemistry Syllabus has the Year 7-10 knowledge as prerequisites, but usually the teacher will cover this content in class just to make sure that you know it, and if you don't, well the syllabus basically makes you learn it again anyway, but in more detail than covered in years 7-10.
As for the "Conquering Chemistry" textbook, firstly, it's a prelim textbook, so if you are doing your HSC in 2018, you'd be better off getting a year 9-10 textbook instead of a prelim textbook (or just don't bother getting one at all tbh unless your teacher isn't that great). Conquering Chemistry will probably go too deep into detail for what you need to know in year 10.
